Temperature Compensation in Antarctic Pteropods: An Integrative Approach

极地水域的生命需要生理特化，以克服反应过程中的温度限制。长期存在的代谢性冷适应假说提出，极地类群的基础代谢率和活跃代谢率相对于温带类群的基础代谢率和活跃代谢率上调，这一假说仍然存在争议，在分类上仅限于鱼类和底栖无脊椎动物。极地翼足目(软体动物：腹足纲)是一种丰富的代谢活跃的分类群，具有潜在的实质性热补偿的生理过程潜在的运动。这项研究将考察两个翼足类动物的新陈代谢冷适应，特别是运动能力的热依赖。冷适应假说将通过比较典型的温带和极地物种以及评估代谢、生物力学和神经基础对运动行为可能的协调热补偿来检验。建议的研究包括三个部分：1)极地和温带姐妹翼足类物种的基础和代谢率的比较，以及线粒体能量学的比较；2)相同翼足目类群的运动生物力学比较，特别是温度降低和粘度增加对运动能力的不同影响；3)游泳系统神经元对不同温度的反应，特别是静息电位、放电阈值、动作电位持续时间和离子通道动力学的比较。通过评估代谢、生物力学和神经反应对水温变化的相似性和联系，将检验极地翼足类动物温度补偿的总体假设。这项研究将为该分类群提供基本的生理和行为信息，将系统地评估翼足类动物组织水平上的冷适应假说，更广泛地将评估在极地水域生活和活动的许多无脊椎动物类群的温度和运动限制的性质。

Life in polar waters requires physiological specialization to overcome thermal limits on reaction processes. The long-standing hypothesis of metabolic cold adaptation, which proposes upregulation of basal and active metabolic rates in polar taxa relative to temperate-zone counterparts, remains contentious and has been taxonomically limited in evaluation to fish and benthic invertebrates. Polar pteropods (Mollusca: Gastropoda) represent an abundant and metabolically active taxon with potentially substantial thermal compensation of the physiological processes underlying locomotion. This research will examine metabolic cold adaptation in two pteropod taxa, with particular reference to the thermal dependence of locomotor performance. Hypotheses of cold adaptation will be tested by comparing representative temperate zone and polar species and by evaluating possibly coordinated thermal compensation of metabolic, biomechanical and neural underpinnings to locomotor behavior. The proposed research comprises three parts: 1) comparison of basal and metabolic rates of sister pteropod species from polar and temperate zones, together with comparisons of mitochondrial energetics; 2) comparison of locomotor biomechanics for the same pteropod taxa, with particular reference to the differential effects of reduced temperature and concomitantly increased viscosity on locomotor performance and 3) comparison of the responses of swim system neurons to variable temperatures, with particular reference to resting potentials, firing thresholds, action potential durations and ion channel kinetics. The overall hypothesis of temperature compensation in polar pteropods will be tested by evaluating similarities and linkages in metabolic, biomechanical and neural responses to variable water temperature. This research will provide fundamental physiological and behavioral information for this taxon, will systematically evaluate the hypothesis of cold adaptation across organizational levels in pteropods, and more generally will evaluate the nature of thermal and locomotor constraints for the many invertebrate taxa living and moving within polar waters.